While fish, ducks, beavers, and various other animals either live in, or make frequent natural use of rivers, lakes, and streams, there are many occasions when their presence is not desired. Beavers are a very destructive breed of mammal and can chew up many trees and vegetation that are stream or river-based in a short time. For similar reasons muskrats, Norway rats, and occasionally even ducks, geese, and birds are desired to NOT be in certain zones. Sometimes, it is even desired to keep certain fish out of specific aquatic areas or zones. The problem, simply presented, is how to repel these animals warm blooded species, fish, et al. from a certain zone, or depth of water in said zone, in an automatic manner without causing them permanent physiological harm.
The instant inventor's solution to this problem is to apply his previous theories of scientifically-based levels of "safely" electroshocking specific species while in the water of said zone/volume in conjunction with sensors to detect these species when they enter the zone/volume of water to be protected. For example, warm-blooded animals can be detected by sensitive infrared means and cold blooded animals may be detected with ultrasonic sensors. In this manner the power/electrical energy needed to repel the "undesired" animal will be conserved to that used only when said animal is detected in the "to-be-repelled-from" or "protected" zone. The volume of water actually electrified can be controlled through the design and configuration of the electrode arrays. The physical size of the conductive electrodes can be also used as an additional control to limit the magnitudes of the power densities developed in the water.
Prior art related to electrofishing and similar electrical energy applied to volumes of water to have a desired non-lethal effect on fish and other aquatic animals includes:
Kolz, A. L. 1989, "A Power Transfer Theory for Electrofishing", in Electrofishing, A Power Related Phenomenon, U.S. Fish & Wildlife Service Tech. Report 22(1989),pp 1-11;
Kolz, A. L. Reynolds, J. B., 1989, "Determination of Power Threshold Response Curves", Ibid pp. 15-24.
Other related publications include:
Kirkpichenko, M. Ya, V. P. Mikheev, & E. P. Shtern, 1963, "Action of Electric Current on Dreissena polymorpha larvae and planktonic crustaceans with short Exposures", Akad. Navk SSSR, Moscow, 1963, pp. 76-80.
Shentiakov, V. A., 1961, "Deistvie elektricheskogo toku promyshlennoi chastoty na kolonii Dreissena", Biull. Int. biol. vodokhr. AN SSSR, No.10.
Also see U.S. Pat. No. 5,289,133, "power Density Methods for Electroshocking" by the same inventor (filed Jan. 19, 1993 as Ser. No. 08/5966 as divisional of Ser. No. 677,930 filed Apr. 1, 1991, now U.S. Pat. No. 5,202,638).", has been deleted.
The intensity of the electrical shock received by an animal immersed in water is determined by the magnitude of the electrical power density present in the water and the effective conductivity of the animal (Kolz, 1989)). In general, the electroshock response of an animal progresses through the stages of mild irritation, extreme agitation, electronarcosis (stunned), tetany, and death, as the intensity of the electrical field is increased.
In the following table, Table I, are listed the approximate thresholds of power density for the three electroshock responses of excitation, stun, and death, as reported by various researchers for three species of fish, two species of mussels, Norway rats, mallard ducks, and Canadian geese. Except for the goldfish data shown in FIG. 1 (as measured by Kolz & Reynolds (1989), these data are extrapolated from isolated and fragmentary experiments, and the values listed in said Table are only indicative of a relative magnitude and not an absolute value. Nonetheless, the information is presented in order to show how these electroshock responses can be used to develop animal control devices.
The power density thresholds for all of the animals listed in said Table indicate that the animals are excited and disturbed by the electrical energy at power density levels much lower than that required to stun or kill the animals. This knowledge is the basis for the invention's concepts relating to the development of electroshock techniques to control animals. Animals will simply not colonize or remain in a zone/area where they are made physically uncomfortable. In the experiments with fish, ducks, geese, beaver and Norway rats, the animals escaped from the electrical fields as quickly as possible. The only animals to remain in the electrical fields were those that were incapacitated by muscular tetany or actually stunned by the electroshock effects. These data support the premise that animals can be controlled without serious injuries or harmful effects using electroshock. The methods taught are certainly more acceptable to the general public than control methods that result in lethal effects.
The Kolz research disclosed here teaches that the use of alternating current polarity waveform is considered more desirable for warm blooded animal repulsion than direct current or pulsed direct current waveforms at different levels of power density although direct current waveforms can be used. A power density of about 120 microwatts per cubic centimeter was determined to be adequate to disrupt the behavior of Norway rats and cause them to be repelled. The beaver is a larger member of the same Rodentia class as the Norway rat and is repelled in a similar manner. Aquatic birds, such as ducks and geese, are also repelled by electrical fields in water even though the bird's feathers partially insulate the birds from full and direct electrical contact with the water.
Electrified water barriers will protect waterways and impounding structures (such as headgates and dams) from damage caused by aquatic mammals, protect crops (such as rice paddies) from rodent damage, protect waterfowl from predators, and protect grain storage facilities from rodent infestation.
The electroshocking repulsion system is advantageous because it is only activated (turned on) when a target warm-blooded animal is detected by an appropriate sensor such as an infrared detector. Cold-blooded animals could be detected by appropriate sensors such as ultrasonic devices, an interrupted light beam, or a pressure transducer. The electroshock is applied to the animal through the water by means of an electrical field that is generated from an array of electrodes. The size, shape, and intensity of the electrical field(s) are independently controlled under determined criteria to cause specific animal repulsion or tetanization, although fatal effects could also be engineered if desired.